Pillow

ABSTRACT

Pillow  1  according to the present invention includes a main body  3  having a concave portion  7  in the central part, and a cold insulator  5  mounted in the concave portion  7.  This concave portion  7  is open in the central part of the main body side wall  8  on the side where the human nape is to be situated. The cold insulator  5  has a film for inclusion  11,  and a gel material  9  which is internally included in the film for inclusion  11  and which includes a crosslinked polymer that is not in a swelled state with a medium. It is preferred that the gel material  9  includes an unfoamed polyurethane resin, and has an Asker F hardness of 10 or greater and 50 or less. Also, depth of the opening of the concave portion  7  that is open at the main body side wall  8  is preferably equal to or greater than one third of the height of this main body side wall  8.  This pillow  1  is constituted so that the head region can be held with a shape fitting the shape of the neck and head, therefore, any strain is not imposed to the body.

This application claims priority on Patent Application No. 2003-312629 filed in JAPAN on Sep. 4, 2003, Patent Application No. 2004-204543 filed in JAPAN on Jul. 12, 2004 and Patent Application No. 2004-257170 filed in JAPAN on Sep. 3, 2004.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to pillows. In particular, the present invention relates to pillows for use in cooling human neck and head region.

2. Description of the Related Art

Conventionally, water pillows have been used for cooling a head region. The water pillow is troublesome in replacement of ice and water. For the replacement, place, vessel and the like for dealing with water are required. A variety of means have been proposed in order to eliminate the burden. For example, JP-A No. 2002-330986 describes an invention concerning a pillow including capsules without need of water. In this pillow, cooled capsules are packed in stead of ice.

Also, JP-A No. 2001-297 describes an invention concerning a pillow in which a cold insulation member is placed in a pocket provided to a pillow cover. As the cold insulation member, commercially available product may be used. This has a simple sheet form and has a small thickness. Thus, contact area with ambient air is great resulting in inferior cold insulation ability.

JP-A No. 2001-198151 describes an invention concerning a quickly cooled type cooling package body comprising two sheet members. Powder of at least one sort of absorbing substance which absorbs salt water to be gelatinized is included in one sheet member of this package body, while at least one sort of water absorbing resin to which water is added to be hydrated and gelatinized, and a mold-proofing/antiseptic agent are included in another sheet member. By allowing these two sheet members to be communicated, the coolant is brought into contact with water to cause an endothermal dissolution reaction thereby exerting a rapid cooling action.

JP-A No. H07-163448 describes an invention concerning a pillow having a bag body which is packed with a gel material and is embedded into a concave section provided at a lowered portion in the central part of a pillow core material (main body). As this gel material, a mixture of a super absorbent resin and water, and polyurethane foam with communicating bubbles to which water is introduced are illustrated. In this bag body, volume of the concave section is limited leading to lack in cold insulation ability, and the limited position of the bag body to the area corresponding to the head region results in a problem of confinement of the area of the cold insulation only to a part of the head region.

SUMMARY OF THE INVENTION

In connection with shape of pillows, it has been believed that shapes capable of allowing the cervical spine to maintain a similar shape to that in the uprising posture are favorable because of no strain to the body. To this end, it is necessary to maintain the shape of a pillow constant while securing stability and comfort during sleep when the pillow is placed under the head region. In order to maintain the shape of a pillow, it is necessary to have a restoring property. Any one of the pillow and package body described above is deformed as the head region moves, and thus, it does not have a shape conservation feature similarly to conventional water pillows. To the contrary, when the shape conservation ability is too great, stability at the head region and comfort during sleep may be deteriorated due to inferior shape following capability. In other words, flexibility is required in order to improve the stability at the head region and comfort during sleep. The present invention was made taking into account of the circumstances as described above, and an object of the invention is to provide a pillow which can hold and cool the head region with a shape fitting the shape of the neck and head without imposing strain on the body, and which is excellent in comfort during sleep while maintaining cooling function, because it has appropriate hardness and resilient property.

The pillow according to the present invention comprises a cold insulator having a film for inclusion and a gel material which is internally included in the film for inclusion and which comprises a crosslinked polymer that is not in a swelled state with a medium, and a main body having a concave portion which is open in the central part of the side wall thereof and which is constituted so that the above-mentioned cold insulator is mounted in the above-mentioned concave portion.

The above-mentioned gel material comprises 10% by weight or greater and 40% by weight or less of a latent heat storage medium having a melting point of 10° C. or greater and 20° C. or less, being in a powder form having a particle size of 1 μm or greater and 50 mm or less, and comprising an organic compound, in a state being encased in a capsule of a synthetic resin film.

After setting the temperature of the above-mentioned cold insulator to be 5° C., surface temperature at a position in contact with the neck region is kept at 5° C. or greater and 25° C. or less for at least 1 hour, when an adult man with a body temperature of approximately 36° C. lies thereon in an atmosphere of at 26° C. When the temperature of the above-mentioned cold insulator is set to be 20° C., the hysteresis loss is 5% or greater and 50% or less, and the spring constant is 0.1 N/mm or greater and 0.7 N/mm or less as measured upon compression with a compressing element having a diameter of 10 mm at a testing rate of 30 mm/min. When the thickness is less than 30 mm, the measurement is carried out with overlaid samples.

The spring constant herein refers to a value of stress/displacement when a compressing element having a diameter of 10 mm is pressed in at a testing rate of 30 mm/min. Further, the hysteresis loss indicates a proportion of area of the hysteresis loop in a stress-strain curve. Method of calculation of the hysteresis loss is as follows. First, alteration of the amount of deflection S of the gel material is measured in both of: the case in which a compression stress Sc is loaded on the gel material; and the case in which load of this stress Sc is removed. Then, area of the hysteresis loop (S₁−S₂) is calculated from an integration value of an upward curve yielded when the compression stress Sc is increased, and an integration value of a downward curve yielded when the compression stress Sc is decreased. Furthermore, the proportion (%) of the area of the hysteresis loop (S₁−S₂) to an integration value S₁ of the upward curve described above is determined according to the following formula (1): (S ₁ −S ₂)/S ₁×100   (1)

The above-mentioned gel material comprises a crosslinked and unfoamed polyurethane resin, and has an Asker F hardness of 10 or greater and 50 or less.

The cold insulator may be in a sheet form. Preferably, the cold insulator in a sheet form has a thickness of equal to or less than 25 mm. The cold insulator in a sheet form can be encased in a container in a rolled state or a folded state.

The cold insulator provided to the pillow of the present invention can keep a temperature giving a moderately cool feeling, i.e., 5° C. or greater and 25° C. or less, for a long period of time through previously cooling it by e.g., storing in a refrigerator, or the like, even if it is left to stand at a room temperature thereafter. This temperature is suited for getting a comfortable quiet sleep through cooling the head region and neck region. In addition, because there is no risk to cause frostbite within this temperature range, it may be used to cool the head region and the like of infants and elderlies without anxiety.

Because the cold insulator comprises a gel material, and this gel material itself has a shape conservation property and elasticity, when it is used in a pillow, the head region can be held and cooled with a shape fitting the shape of the nape and head thereby imposing no strain to the body.

For reference, JP-A No. H07-265348 describes an invention concerning a pillow including a cold insulating material for the cold insulation of the head region at a temperature that is lower than the body temperature by approximately 5 to 10° C., and JP-A No. H07-298971 describes an invention concerning a pillow including a cold insulating material that keeps the temperature of approximately 32° C. even though it is heated. It is believed that the temperature for cold insulation was predetermined to fall within the temperature range as described above in these pillows on the basis of an idea that a quiet sleeping effect may be achieved as long as some degree of coldness is felt on a hot night in summer. However, as is clear from Examples described later, such a condition to keep cold at a temperature that is lower than the body temperature by approximately 5 to 10° C. is insufficient for achieving a quiet sleep on a sultry night with the outside air temperature being not less than 25° C. Moreover, according to the pillows described in JP-A No. H07-265348 and JP-A No. H07-298971, because the bag body including the cold insulating material is segmentized, they involve problems of incapable of persisting cooling effect since the weight of the cold insulating material at the part to be in contact with the head region is lessened, and efficiency of heat conduction is also decreased.

The cold insulator included in the pillow of the present invention maintains the compression stress and hysteresis loss within the range described above even if it is cooled to 5° C., thereby exhibiting an appropriate hardness and resilient property. Therefore, the pillow of the present invention is suitable as one bedding for achieving a quiet sleep under hot circumstances such as in summer, particularly on a sultry night.

When a latent heat storage medium is encased in a capsule, the capsule itself can be retained in a solid or a powder form even when phase conversion is caused in the latent heat storage medium according to alteration of the temperature. Thus, any influence on the entire state of the gel material including the latent heat storage medium can be prevented.

According to the pillow which comprises a main body having a concave portion in the central part and a cold insulator mounted in this concave portion, the head region is cooled by the cold insulator in a state of holding the head region with a shape fitting the shape of the nape and head thereby imposing no strain to the body. In addition, the cooling effect persists owing to the mounted cold insulator. Also, there exist multiple kinds of cold insulators to be mounted, which can be replaced. Selection of the cold insulator enables adjustment depending on the physical constitution, as well as the user and situation.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view illustrating a pillow according one embodiment of the present invention;

FIG. 2(a) is a plan view of FIG. 1; FIG. 2(b) is a front view of FIG. 1; and FIG. 2(c) is a side view of FIG. 1;

FIG. 3 is a cross sectional view depicted along the line III-III shown in FIG. 2;

FIG. 4 is a cross sectional view depicted along the line IV-IV shown in FIG. 2;

FIG. 5 is a plan view illustrating a pillow according to another embodiment of the present invention;

FIG. 6 is a front view illustrating the pillow shown in FIG. 5;

FIG. 7 is a right side view illustrating the pillow shown in FIG. 5;

FIG. 8 is an exploded perspective view illustrating a pillow according to still another embodiment of the present invention; and

FIG. 9 is an exploded perspective view illustrating the state in which the cold insulator of the pillow shown in FIG. 8 is refrigerated.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention is hereinafter described in detail with appropriate references to the accompanying drawing according to the preferred embodiments.

Pillow 1 according to one embodiment of the present invention is depicted in from FIG. 1 to FIG. 4. FIG. 1 is a perspective view of the pillow 1. FIG. 2(a) is a plan view; FIG. 2(b) is a front view; and FIG. 2(c) is a right side view of the pillow 1. FIG. 3 is a cross sectional view depicted along the line III-III shown in FIG. 2. FIG. 4 is a cross sectional view depicted along the line IV-IV shown in FIG. 2.

The pillow 1 comprises a main body 3 and a cold insulator 5. The main body 3 has a concave portion 7 for mounting the cold insulator 5. This concave portion 7 is provided by cutting off in a length (back and forth) direction in the central part of the main body side wall 8 on the side where the human nape is to be situated. The side where the human nape is to be situated is defined on the side of one long edge of the main body 3. The cold insulator 5 has a contour almost meeting with the shape of the concave portion 7 such that it is mounted in the above-mentioned concave portion 7. The cold insulator 5 is mounted in this concave portion 7. The pillow 1 is used with such a combination of the main body 3 and the cold insulator 5 accordingly. Plane shape of the contour formed by the combination of the main body 3 and the cold insulator 5 is a rectangle. Although the size of this pillow 1 not particularly limited, however, it has usually a width L of 400 mm or greater and 1000 mm or less, a length W of 300 mm or greater and 500 mm or less and a height of the above-mentioned side wall 8 of 10 mm or greater and 190 mm or less.

In the example illustrated in FIG. 2(b), the depth P of the opening of the concave portion 7 that is open to the main body side wall 8 accounts for about 83% of the height H of this main body side wall 8. When the depth P of this opening is too small, sufficient cold insulation effect is not achieved because the volume of the cold insulator 5 becomes so small. Preferably, the depth P of this opening is equal to or greater than one third (⅓) of the height H of the main body side wall 8. The depth P of the opening may be equal to the height H of the side wall 8. As described later, the shape of the concave portion 7 is defined corresponding to the shape of the cold insulator 5 determined taking into consideration of the human physical constitution. Change of the shape (predominantly, height and shape of the curved face) of the cold insulator 5 mounted in this concave portion 7 may be considered. In other words, the concave portion 7 is formed so that smooth entire shape of the pillow 1 is generated in combination with the cold insulator 5.

It is preferred that the main body 3 has a hardness to enable the human head to be supported, and has flexibility as well as restoring property. Thus, a rubber or synthetic resin material is preferably used in the main body 3. Examples of the rubber which may be used include natural rubbers, isoprene rubbers, butadiene rubbers, styrene-butadiene rubbers, acrylonitrile-butadiene rubbers and the like. The synthetic resin material which may be used is one or two or more thermoplastic elastomers such as polyurethane, polyester, polyamide, polyolefin, polystyrene, polyvinyl chloride, silicone, polybutadiene and the like. In terms of possible regulation of the flexibility and a variety of hardness, material of the main body 3 is preferably a polyurethane foam. Above all, a polyurethane foam having a low resilient property is preferred. The main body 3 may be obtained through forming the material with a molding method such as injection molding, extrusion molding or the like.

The hardness and resilient property of the cold insulator 5 may be predetermined so that it becomes suited for a pillow on which the head region and neck region is placed. Particularly, when the cold insulator 5 has great flexibility (also referred to as softness) and has a low shape conservation ability, it is formed so that the cold insulator 5 is held to have a shape falling within a predetermined scope due to the concave portion 7. For example, a material having low flexibility and great shape conservation property may be selected for the main body 3. Alternatively, surface material of the circumferential side wall constituting the concave portion 7 may be thickened, thereby making the shape of the concave portion 7 difficult to be changed. Also, circumferential part of the concave portion 7 may be composed of a material having an elasticity modulus higher than that of the material of the main body 3.

In the concave portion 7 may be mounted the cold insulator 5 which may be replaced as described later. To this end, the concave portion 7 has a shape fitting the shape of the cold insulator 5. However, presence of a small space may be permitted for accepting the error in size of multiple types of the cold insulators 5 which are separately manufactured. Also in cases where no space is present, because the main body 3 and the cold insulator 5 have flexibility, the cold insulator 5 can be mounted within the range of the flexibility. However, too great space is not preferred because a predetermined shape may not be maintained such as e.g., occurrence of too deep sinking down of the head region.

The concave portion 7 may be disposed on the basis of the size and position where the nape and back region of the head is placed upon use. When this pillow 1 is used, a curved face is formed which agrees with the shape of from the nape to the back region of the head when the human is in the uprising posture. The shape of this curved face may be also formed by the cold insulator 5 which has softness, and is supported by the main body 3 having a shape conservation property.

As shown in FIG. 3 and FIG. 4, the height of the main body 3 is lessened in a part on which the back region of a human head is to be situated. The height of the pillow 1 is increased in a part on which the posterior neck region close to the shoulder is to be situated. When the cold insulator 5 is large, this shape is primarily maintained by the cold insulator 5. When the cold insulator 5 is small, the predetermined shape is primarily maintained by the shape of the main body 3.

The main body 3 has flexibility which enables following to deformation in the state in which the cold insulator 5 is mounted. Human shall turn over and displace the head. In order to improve the following capability to deformation, a material having a low resilience elasticity modulus is desired. Inferior comfort during use may be provided unless some degree of following capability is present in the main body 3 as well as this concave portion 7. Therefore, the pillow 1 is designed so that it has moderate flexibility and restoring property, thereby enabling the head region to be supported while dispersing the weight of the head region to the entire surface of the head region.

It is preferred that the main body 3 has multiple depressions D on the surface thereof. The depressions D prevent close contact of the human head region and the like with the main body 3 when the pillow 1 is placed under the head region and the like. In other words, a space is formed between the head region and the like and the main body 3. Because this space provides air permeability, sticky feeling or stuffy feeling is not caused. The depressions D are formed by providing grooves, holes, protrusions or the like on the surface. The pillow 1 has multiple grooves in a direction that agrees with the longitudinal direction of the front face. Depth, intervals and the like of the grooves may be determined so that favorable comfort during use is achieved in accordance with the properties of the main body 3 and the cold insulator 5.

The cold insulator 5 has a cold insulating material 9 and a film for inclusion 11 for including this cold insulating material 9. The front face shape of the cold insulator 5 is formed so that it fits the curved face of from the nape to the back region of the head in the uprising posture. The cold insulator 5 is produced separately from the main body 3, and is independent. The cold insulator 5 may be prepared of multiple kinds per one main body 3. The cold insulator 5 alone can be detached from the main body 3, and then cooled or frozen. Any cold insulator 5 having a different shape, i.e., height (thickness), curved shape of the surface and the like, can used for replacement as long as it is mounted in the concave portion 7 of the main body 3. In addition, multiple kinds thereof with the cold insulating material 9 having different hardness, cold insulation performance and the like may be also prepared. These may be selected ad libitum depending on the circumstances.

The cold insulator 5 has usually the size with: a width N of 100 mm or greater and 500 mm or less, a length M of 150 mm or greater and 500 mm or less and a height of 10 mm or greater and 190 mm or less. Height of the cold insulator 5 may be adjusted so that the neck can be supported in combination with the main body 3. The height of the cold insulator 5 may vary depending on the depth of the posterior neck region and the distance between the shoulder and temporal head region in the side-lying position of the human who use it, and on the preference.

As described above, this cold insulator 5 forms a part of the pillow 1 by being embedded into the central part of the main body side wall 8, with a certain thickness. Three side faces of the cold insulator 5 to be in contact with the main body 3 are protected from the outside by the main body 3 comprising a foam or the like. Because the foam of the main body 3 adjacent to the side faces exhibits a thermal insulation property, less thermal conduction from the side face of the cold insulator 5 is attained. Therefore, area of the front face side of the pillow 1 on which heat from the outside is conducted becomes relatively small with respect to the cold insulator 5. Owing to this combined structure, extra heat from the outside is difficult to be conducted to the cold insulator 5. Thus, this pillow 1 exhibits a persistent cooling action.

The cold insulator 5 also has certain degree of shape conservation ability while supporting the weight of the head and neck. This function can reduce strain on the neck when a human places the head on the pillow 1. When this shape conservation property is too great, excessive hardness is liable to be provided. When the cold insulator 5 is too hard, following capability to the deformation becomes deficient upon displacement of the head or the neck, and the like. Unless some degree of following capability to the deformation is present, comfort during use is deteriorated. The cold insulator 5 has flexibility which enables to follow to the deformation. Accordingly, appropriate flexibility and restoring property is provided to enable supporting while dispersing the weight of the head region to the entire surface of the head region.

The cold insulator 5 may be generally used in the state in which surface temperature falls within the range of 5° C. or greater and 30° C. or less. The cold insulator 5 preferably has a surface temperature of 10° C. or greater and 25° C. or less. More preferably, the temperature is 12° C. or greater and 20° C. or less. A gel material comprising a crosslinked polymer without including a medium is used as the cold insulating material 9. This gel material comprising a crosslinked polymer without including a medium is preferable as the cold insulating material 9 in light of the shape conservation property and elasticity residing in the gel material itself. Herein, “without including a medium” means that not being in a swelled form with a medium, which is distinct from the case of containing a small amount of oil and the like as an additive. Specifically, content of the medium is equal to or less than 50% by weight per the crosslinked polymer.

This gel material is obtained by crosslinking of unfoamed urethane. The polyurethane resin is obtained by compounding polyol, polyisocyanate and a crosslinking agent (curing agent) to execute crosslinking. Examples of representative curing method include a prepolymer method in which polyol and polyisocyanate are previously subjected to a reaction, and a one-shot method in which the above-mentioned components are concomitantly compounded. It is preferred that the gel material has an Asker F hardness of 10 or greater and 50 or less. This unfoamed polyurethane may be obtained by any method as long as the Asker F hardness is adjusted to fall within this range. In the present invention, the Asker F hardness is measured by a method in conformity to a durometer hardness test established in JIS-K6253. Upon specific measurement, Asker F hardness scale available from Koubunshi Keiki Co., Ltd. may be used. When the subject of measurement has potent adhesiveness, a film which does not inhibit free distortion of the subject of measurement is interposed between the hardness scale and the subject of measurement, and thus, the hardness of the subject of measurement is measured.

When the Asker F hardness is less than 10, it becomes too soft leading to lack in stability. In this respect, the Asker F hardness is more preferably equal to or greater than 20. Still more, the Asker F hardness is preferably equal to or greater than 25. When the Asker F hardness is greater than 50, tactile sensation may be hard resulting in inferior comfort during sleep. In this respect, the Asker F hardness is more preferably equal to or less than 40. More preferably, the Asker F hardness is equal to or less than 35.

Examples of the isocyanate compound to be a material of the above-mentioned urethane prepolymer include diphenylmethane diisocyanate (MDI), modified MDI such as polymeric MDI and liquid MDI, hydrogenated tolylene diisocyanate (TDI), hydrogenated MDI, hexamethylene diisocyanate (HMDI), xylylene diisocyanate (XDI), naphthalene diisocyanate (NDI), triphenylmethane triisocyanate and polymethylene polyphenyl isocyanate.

The above-mentioned polyol which may be used has an average functional group number of from 2 to 4, and an average molecular weight of from 50 to 6000. For example, low molecular weight bivalent or trivalent alcohol, polyether polyols, condensed polyester polyols, polymerized polyester polyols, polycaprolactone polyols and the like may be used. Examples of suitable polyol include low molecular weight alcohols such as ethylene glycol, propylene glycol and 1,3-butanediol; polyoxypropylene glycol (PPG), polyoxypropylene triol, polyoxypropylene-polyoxyethylene-triol, polyoxytetramethylene glycol, polyalkylene ether polyols and the like.

The polyurethane prepolymer is synthesized by, for example, compounding an isocyanate compound and polyol in an equivalent ratio (NCO/OH) of the isocyanate group (NCO) carried by the isocyanate compound and the hydroxyl group (OH) involved in the polyol being from 1.3 to 5, followed by allowing a reaction at approximately from 50° C. to 120° C. for around 3 to 10 hours. The viscosity is preferably within the range to exhibit a liquid state having a low viscosity at an ordinary temperature in terms of the working property and the like. Content of the isocyanate group in the polyurethane prepolymer is generally from 1% by weight to 15% by weight. Preferably, the content of the isocyanate group is from 2.5% by weight to 10% by weight. Liquid viscosity of the polyurethane prepolymer is preferably from 2000 to 20000 CPS (at 25° C.) in terms of the working property.

As a curing agent, a compound having an active hydrogen may be used. For example, a curing agent containing polyol may be suitably used in curing the urethane prepolymer. Above all, poly(oxyethylene) polyol, poly(oxyethylene propylene) polyol and polytetramethylene ether glycol are suitable, and those having a molecular weight of from 300 to 6000 and having 2 to 4 functional groups are preferred.

Hardness of this gel material may be adjusted by altering the degree of crosslinking through changing the type or compounding amount of the curing agent, or by using an additive such as a catalyst. As the catalyst, an amine based catalyst such as tolylene diamine, lead octylate, dibutyltin dilaurate or the like may be used alone or in combination of two or more thereof. A composition containing polyol, polyisocyanate and a curing agent may be heated at from 50 to 150° C. for approximately from 1 to 120 minutes to perfect crosslinking.

It is more preferred that a latent heat storage medium is compounded into this composition of unfoamed polyurethane. The latent heat storage medium which may be used is one which is gradually molten while elevating the temperature of the cold insulating material 9, and absorbs the heat while melting. The latent heat storage medium for use in the cold insulating material 9 has a melting point of preferably 5° C. or greater and 30° C. or less, and particularly preferably 10° C. or greater and 20° C. or less. Examples of the latent heat storage medium include paraffin such as n-tetradecane (m.p. 5.9° C.), n-pentadecane (m.p. 9.9° C.) and n-hexadecane (m.p. 18.2° C.); aliphatic saturated monocarboxylic acid esters such as tridecyl caproate (m.p. 7° C.), pentadecyl caproate (m.p. 16° C.), methyl laurate (m.p. 5° C.), methyl tridecanoate (m.p. 20° C.), methyl myristate (m.p. 19° C.), ethyl myristate (m.p. 12° C.), methyl pentadecanoate (m.p. 19° C.), ethyl pentadecanoate (m.p. 14° C.), butyl palmitate (m.p. 18° C.) and amyl palmitate (m.p. 19° C.); aliphatic saturated dicarboxylic acid esters such as dimethyl succinate (m.p. 19° C.), dimethyl adipate (m.p. 9° C.), dimethyl 1,9-nonane dicarboxylate (m.p. 20° C.), diethyl 1,9-nonane dicarboxylate (m.p. 16° C.), diethyl 1,10-decane dicarboxylate (m.p. 16° C.) and diethyl 1,11-undecane dicarboxylate (m.p. 20° C.); alcohols such as 1-decanol (m.p. 7° C.), 1-undecanol (m.p. 16° C.) and2,3-dibromo-1-pentanol (m.p. 13° C.), and the like. Among them, n-paraffin such as n-pentadecane is more preferred in terms of excellent phase conversion stability and great amount of thermal storage.

With respect to the latent heat storage medium according to the present invention, combination of the gel material with other component as well as content of the latent heat storage medium in the gel material must be predetermined in light of making the cold insulation effect of the cold insulator 5 appropriate, and preventing to make the cold insulator 5 too hard or to make it too soft, to the contrary.

This latent heat storage medium such as n-paraffin is preferably encased in a capsule formed with a resin film of an acrylic resin, a melamine based resin or the like. This capsule containing the latent heat storage medium is compounded in the urethane prepolymer composition. Specific examples of the capsule containing the latent heat storage medium include “Heat Storage Micro Capsule Solid Granulated Material” (manufactured by MITSUBISHI PAPER MILLS LIMITED., Research Center). This “Heat Storage Micro Capsule Solid Granulated Material” comprises a mixture, which contains n-paraffin as a principal component, being encased into a microcapsule. Because this n-paraffin has a melting point of approximately 15° C., a low temperature can be comfortably kept for a long period of time.

The capsule containing the latent heat storage medium such as n-paraffin is preferably included in an amount of 10% by weight or greater and 40% by weight or less per total amount of the gel material. When the content of the capsule is less than 10% by weight, keeping an adequate temperature for a long period of time may be impossible. To the contrary, when this content is greater than 40% by weight, content of the gel material becomes too low, which may result in failure in retaining the shape thereof, or make the gel material too hard at a low temperature. Thus, in connection with the content of the capsule, in particular, it is preferred that lower limit is 20% by weight, while upper limit is 30% by weight.

Content of the latent heat storage medium such as n-paraffin is preferably determined to account for 40% by weight or greater and 90% by weight or less in total amount of the capsule containing the latent heat storage medium. In connection with the content of the latent heat storage medium, in particular, it is preferred that lower limit is 50% by weight, and still more, 60% by weight,while upper limit is 80% by weight,and still more, 70% by weight The heat of fusion of the capsule containing the latent heat storage medium is preferably equal to or greater than 100 J/g,more preferably equal to or greater than 150 J/g, and particularly preferably equal to or greater than 200 J/g.

The gel material is obtained by filling a forming material in the film for inclusion 11 having a predetermined shape followed by perfecting crosslinking. The gel material may be also obtained by casting a forming material into a metal mold, or extrusion molding with an extruder, and thereafter, allowing crosslinking.

The film for inclusion 11 of the gel material is not particularly limited as long as it is not broken with a certain degree of external force, does not exude the gel material, and is not altered due to the gel material. In particular, in case of the gel material being two-component cured type polyurethane, a silicone rubber or the like, when raw materials such as polyurethane are filled into a back made from the film for inclusion to allow the materials to be crosslinked and cured, the film material must be selected which does not permit leakage of these raw materials before curing, as well as the polyurethane, silicone rubber and the like post curing. Examples of this film for inclusion include, e.g., films made from a synthetic resin such as polyurethane, polyethylene, polypropylene, polyester, polyethylene-terephthalate (PET), polybutylene-terephthalate (PBT), polyamide, polyvinyl chloride, polyvinylidene chloride or the like. Also, it may be a composite film or a laminated film of these films, or a film with aluminum or the like vapor-deposited on the surface of the same. Among the above-illustrated films for inclusion, a film made from polyurethane is preferred which readily achieves mechanical characteristics suited for the cold insulator of the present invention, and which is excellent in softness, retractility and durability. Particularly, when thermosetting polyurethane is used as the gel material, use of polyurethane as the film improves adhesiveness of the two, and prevents the gel material from detachment from the film during use of the cold insulator.

The film for inclusion 11 preferably has a thickness of 0.01 mm or greater and 1.0 mm or less. When the thickness is smaller than 0.01 mm, the film for inclusion 11 is liable to be broken, and thus, the durability may be inferior. In this respect, the inclusion film has a thickness of preferably equal to or greater than 0.02 mm, and more preferably, equal to or greater than 0.04 mm. When the thickness is greater than 1 mm, the flexibility may be poor to result in inferior comfort during sleep due to hard feel experienced when the human head is brought-into contact. In this respect, the inclusion film has a thickness of preferably equal to or less than 0.5 mm, and more preferably, equal to or less than 0.3 mm. When the film for inclusion 11 has a thickness below the above range, it becomes liable to be broken, and thus, the durability may be inferior. To the contrary, when the thickness is beyond the above range, softness of the pillow may be deteriorated. It is preferred that the film has a thickness of particularly 0.08 to 0.15 mm.

It is preferred that the tensile strength is 45 to 110 MPa, the degree of elongation is 100 to 800%, and the tear strength is 100 to 200 N/mm. For reference, the tensile strength and degree of elongation of the film for inclusion 11 is measured by a method established in JIS K7181, and the tear strength of the film for inclusion 11 is measured by a method established in JIS K7128-3. When the tensile strength, degree of elongation, tear strength of the film for inclusion 11 is not attained to the range as described above, the film may become liable to be broken, and thus, the durability may be inferior. To the contrary, when each value is beyond the above range, free deformation to fit the body shape during use may be impossible, thereby resulting in deteriorated feel during use and inferior durability.

It is preferred that the cold insulator 5 obtained as described above has a spring constant of 0.1 N/mm or greater and 0.7 N/mm or less when the temperature is set to be 20° C. Moreover, the hysteresis loss is preferably 20% or greater and 50% or less. The spring constant of less than 0.1 N/mm results in excessive softness, while the spring constant of greater than 0.7 N/mm result in excessive hardness, to the contrary. Lower limit is preferably 0.2 N/mm, more preferably 0.3 N/mm, while upper limit is preferably 0.6N/mm, and more preferably 0.5 N/mm. Further, the hysteresis loss of less than 20% results in excessive hardness, while the hysteresis loss of greater than 50% results in excessive softness, to the contrary. Upper limit of the hysteresis loss is preferably 30%.

Weight of the cold insulator 5 according to the present invention is preferably set to fall within the range of from 250 to 1500 g in light of incorporation into a pillow 1. When the weight is less than 250 g, heating storage capacity may be so small that suitable temperature may not be kept. The weight of greater than 1500 g may result in inconvenience in portage, necessity of a long period of time for cooling, and difficulty in cooling throughout the gel material in a uniform manner.

For the manufacture of the cold insulator 5 including the gel material described above, a mold produced to meet with the shape of the human nape and head is prepared. Surface of this mold is covered by the above-mentioned film for inclusion 11. This film for inclusion 11 is brought into close contact with the surface of the mold by air aspiration or the like. Into this mold covered by the film for inclusion 11 is filled an unfoamed polyurethane composition for use in the gel material to be the main body of the cold insulating material 9. On the above-mentioned unfoamed polyurethane composition is filled an unfoamed polyurethane composition prepared to yield a degree of crosslinking higher than that of the previous composition. These compositions are heated at a predetermined temperature of 50° C. or greater and 150° C. or less for a predetermined period of time of from 1 minute to 120 minutes to allow crosslinking, thereby integrating the above-mentioned unfoamed polyurethane composition prepared to yield the higher degree of crosslinking with the film for inclusion 11 to give the cold insulator 5.

Thus resulting cold insulator 5 has a nonflexible basal part 13 having a thickness of 2 mm or greater and 15 mm or less formed at the bottom thereof. When this thickness is less than 2 mm, joint between the film for inclusion 11 and the gel material may be insufficient. In this respect, the nonflexible basal part 13 has a thickness of preferably equal to or greater than 3 mm, and more preferably equal to or greater than 5 mm. When the above-mentioned thickness is greater than 15 mm, softness of the gel material may be diminished. In this respect, the nonflexible basal part 13 has a thickness of preferably equal to or less than 12 mm, and more preferably equal to or less than 10 mm. Because superior integrity of the film for inclusion 11 and the cold insulating material 9 of this cold insulator 5 is achieved, the film for inclusion 11 is hard to be broken, and excellent shape stability of the cold insulator 5 is also achieved.

It is preferred that the surface of this cold insulator 5 has multiple depressions D. When the cold insulator 5 comprises a gel material, the depressions D are formed by the mold. The depressions D provide the cold insulator 5 with air permeability. This cold insulator 5 prevents stuffy feeling resulting from sweating of the human when the human head and neck is directly brought into contact with the cold insulator 5. An exterior covering may be attached to this cold insulator 5 as an exterior of the above-mentioned film for inclusion 11, similarly to the main body 3. Material of this exterior covering may be similar to ones for use in conventionally known coverings. For the exterior covering, natural fibers such as silk, cotton or wool, or synthetic fibers such as polypropylene, polyester, polyamide, polyvinyl alcohol or polyvinylidene chloride may be used. A nonwoven fabric, woven fabric, knitted fabric or the like comprising these fibers may be used. In light of making a pleasant texture, layered products and products having great porosity of the same are preferred. For this exterior covering, natural leather or synthetic leather may be used. However, thickness and the like of this exterior covering should be considered so as not to impair the uneven shape of the surface as described above.

Upon cooling of the human head region and neck region, it has been believed that the body temperature is lowered by 1° C. in 2 hours during in falling asleep. When the pillow 1 is used, the cold insulator 5 which had been previously cooled in a refrigerator or the like is embedded into the main body 3. This cold insulator 5 effectively cools the back region of the head and nape placed on the pillow 1. Excellent cold insulation property is achieved because extra heat is hardly conducted to this cold insulator 5 as described above. Therefore, the cold insulator 5 exerts a cooling action for a long period of time.

FIG. 5 is a plan view illustrating a pillow 17 according to another embodiment of the present invention. FIG. 6 is a front view illustrating the pillow 17 shown in FIG. 5. FIG. 7 is a right side view illustrating the pillow shown in FIG. 5. This pillow 17 has a main body 19 and a cold insulator 21. The main body 19 has a concave portion 25 that is open in the central part of the main body side wall 23 on the side where the human nape is to be situated. In each Figure, the main body 27 is illustrated in the upper part, while the cold insulator 29 which is embedded into this main body is illustrated in the lower part. As shown in from FIG. 5 to FIG. 7, the concave portion 25 is open in the central part of the main body side wall 23 in a length direction. The concave portion 25 is formed by partially cutting off the main body 19. The main body 19 has a comparably small thickness in a part to be the bottom of the concave portion 25. This part prevents the main body 27 part positioned both right and left sides of the concave portion 25 from spreading sidewise.

This cold insulator 21 comprises a cold insulating material 27 which includes a gel material that is a crosslinked polymer without including the medium described above, and a film for inclusion 29 for including the same. On the bottom of this cold insulator 21 is provided a nonflexible basal part 31. This cold insulating material 27 is formed to give a shape fitting the shape of from the nape to back region of the head of a human. Thin and soft film for inclusion 29 does not have a sufficient function of restraining the outer shape. Because this cold insulating material 27 itself has a shape conservation feature, its shape can be maintained without support by the film for inclusion 29. This pillow 17 has a shape fitting the shape of from the nape to back region of the head of a human, with rich flexibility in the cold insulating material 27 of the cold insulator 21. Owing to the cold insulator 21 comprising this cold insulating material 27, the nape and head can be held and cooled without imposing strain on the body. Although not shown in the Figures, numerous depressions are provided on the upper faces of the main body 19 and the cold insulator 21. This pillow 17 provides a prolonged cooling function accompanied by comfort during sleep.

FIG. 8 is an exploded perspective view illustrating a pillow 40 according to still another embodiment of the present invention. This pillow 40 has a main body 42 and a cold insulator 44. This main body 42 has a concave portion 46 in the central part thereof for mounting the cold insulator 44. This cold insulator 44 comprises a cold insulating material and a film for inclusion similarly to the cold insulator 5 shown in FIG. 1. Material of the cold insulating material is similar to that of the cold insulating material 9 shown in FIG. 3. The cold insulator 44 is in a sheet form. Although time period of retaining the cold insulation effect is shorter according to the cold insulator 44 in a sheet form in comparison with the cold insulator 5 in a block form, the most important cold insulation effect prior to and following falling asleep can be exerted.

FIG. 9 is an exploded perspective view illustrating the state in which the cold insulator 44 of the pillow 40 shown in FIG. 8 is refrigerated. This FIG. 9 also illustrates a container 52 which comprises a body 48 and a cap 50. For refrigerating this cold insulator 44, the cold insulator 44 is rolled first. Because the cold insulator 44 is in a sheet form, it can be readily rolled. Next, this cold insulator 44 is placed into the body 48. Then, the cap 50 is covered this body 48. Next, the container 52 is stored in a refrigerator. By storing the container 52 in the refrigerator for a given length of time, temperature of the cold insulator 44 is lowered. The container 52 is then removed from the refrigerator, and the cold insulator 44 is removed from this container 52. This cold insulator 44 is used in combination with the main body 42.

Through using the pillow 40, hair, sweat, hair dressing, perfume and the like may be attached to the cold insulator 44. Foods are usually stored in a refrigerator. Encasing of the cold insulator 44 in the container 52 prevents the foods from being in contact with the cold insulator 44. The container 52 also blocks spreading of the odor from the cold insulator 44 to the foods. This container 52 is responsible for hygiene. Size of the container 52 is determined so that the container 52 can be readily stored in a refrigerator. For example, a container 52 having almost the same size as that of a general bottle for soft drinks is provided. Combination of this cold insulator 44 with the container 52 is responsible for space saving.

In light of inhibition of spreading of the odor, the container 52 is preferably constructed with a material having no air permeability (e.g., synthetic resin). In light of cooling of the cold insulator 44 in a short period of time, the container 52 is preferably constructed with a material having air permeability (e.g., paper). Although spreading of the odor can not be blocked enough with the container 52 having air permeability, contact of the cold insulator 44 with the foods can be blocked. A ventilation hole may be also formed to the container 52.

In light of possibility of easy rolling, the cold insulator 44 has a thickness of preferably equal to or less than 25 mm, more preferably equal to or less than 20 mm, and particularly preferably equal to or less than 15 mm. In light of maintenance of the cold insulation effect, the thickness is preferably equal to or greater than 5 mm. The cold insulator 44 may be folded and encased in the container. In this instance, a box type container may be used.

EXAMPLES

Hereinafter, advantages of the present invention are clarified by way of Examples, however, the present invention should not be construed as being limited by the description of these Examples.

Example 1

A rubber composition containing a natural rubber as a base (100 parts by weight of a natural rubber, 115 parts by weight of a filler, 4 parts by weight of a softening agent, 5.5 parts by weight of zinc white, 1.1 parts by weight of stearic acid, 5 parts by weight a foaming agent, 2 parts by weight of sulfur, 0.9 part by weight of a vulcanization accelerator, 0.6 part by weight of an antiaging agent) was placed into a mold, and allowed to be vulcanized and expanded at 150° C. for 10 minutes to perfect forming. Accordingly, a main body having a concave portion was manufactured. On the other hand, a polyurethane film (thickness: 0.1 mm, tensile strength: 20 N, tear strength: 8 N, elongation at break: 220%) was laid on a mold having a shape corresponding to the shape of the concave portion of the main body, and then, a polyurethane prepolymer prepared by compounding and dispersing 10% by weight of microcapsules containing a latent heat storage medium (powder form) was cast into the mold heated to 90° C. to give a thickness of approximately 30 mm. Thereon was filled a polyurethane composition to be cured so that the thickness becomes 5 mm, followed by allowing crosslinking at 90° C. for 15 minutes. Thereafter, the mold was cooled, and a cold insulator having a weight of 1300 g was took out. This cold insulator was combined with the main body, and then an exterior covering (for main body; cotton 100%) was wrapped to obtain a pillow of Example 1. The latent heat storage medium was n-paraffin having a melting point of 16° C. The heat of fusion of the microcapsules containing a latent heat storage medium was 230 J/g.

Comparative Example 1

Commercially available cold insulator (manufactured by Dunlop Home Products Co,. Ltd., trade name “Yawaraka Yuki Makura (Soft Snow Pillow)”, thickness: 30 mm, length: 190 mm, width: 340 mm) was placed on a commercially available general flat pillow (made from foamed polyurethane, width: 550 mm, length: 380 mm, height: 10 mm, with an exterior covering made of 100% cotton) to give a pillow of Comparative Example 1. This cold insulator contains a hydrogel consisting of a mixture of 1.5% by weight of carboxymethyl cellulose (CMC), 30% by weight of propylene glycol (PG), 10% by weight of urea, 57% by weight of pure water, and 1.5% by weight of other component such as a pigment.

Examples 2 to 13

A cold insulator was produced similarly to Example 1 except that the melting point of n-paraffin as a latent heat storage medium, -or the amount of the microcapsule containing the latent heat storage medium was altered. This cold insulator was combined with the main body to obtain pillows of Examples 2 to 13. The cold insulator in Examples 5 and 6 is in a sheet form, which cold insulator obtained by filling microcapsules containing the above-mentioned polyurethane prepolymer and latent heat storage medium in a pouched sheet, without filling the polyurethane composition to be cured.

[Evaluation Test of Pillow]

(1) Determination of Temperature Change

The cold insulators of the above-mentioned Examples and Comparative Example were left to stand in a refrigerator (temperature inside: 5° C.) for 8 hours or longer, and thus, the internal temperature of the gel material was regulated to be 5° C. Next, an adult male whose body temperature was approximately 36° C. lay thereon in a room the temperature of which was set at 26° C., and change of the surface temperature on this cold insulator at a position where the neck region of this adult male was in contact was determined.

(2) Evaluation of Mechanical Characteristic

Temperature of the cold insulators of the Examples and Comparative Example were regulated to be 20° C. Then, hysteresis loss (%) and spring constant (N/mm) on compression of the cold insulator were measured. Upon the measurement, Autograph “AGS-5KNG” manufactured by Shimadzu Corporation was used.

(3) Evaluation of Characteristic as Pillow

Thirty subjects at the age of twenties to forties (including 10 women and 20 men) actually used the cold insulators of the Examples and Comparative Example as a pillow for sleeping at night, respectively, and evaluated on comfort during sleep. Evaluation was carried out with 5-point scale in which favorable comfort during sleep was scored as 5, and unfavorable case was scored as 1. Mean score from all the subjects was calculated. Upon evaluation, the cold insulator which had been left to stand in the refrigerator (temperature inside: 5° C.) for 8 hours or longer, respectively, and regulated so that the internal temperature of the gel material became 5° C. was used. Further, the room temperature during sleeping was regulated to be 26° C.

Results of the evaluation tests as described above are presented in Table 1 and Table 2 below together with melting point of the latent heat storage medium, and content of the microcapsule containing the latent heat storage medium. TABLE 1 Example Example Example Example Example Example Example Example 1 2 3 4 5 6 7 8 Melting point of latent heat 16 16 16 16 16 16 10 20 storage medium (° C.) Content of capsule containing 10 20 30 40 20 40 20 40 latent heat storage medium (% by weight) Asker hardness F of gel material 32 34 40 44 35 46 33 43 Spring constant of cold insulator 0.35 0.39 0.50 0.70 0.40 0.65 0.37 0.69 (N/mm) Hysteresis loss of cold insulator 8 11 25 50 12 48 11 50 (%) Weight of cold insulator (g) 1300 1300 1300 1300 600 250 1300 1300 Thickness of cold insulator (mm) 35 35 35 35 16 7 35 35 Comfort during sleep 4.5 4.7 4.7 3.1 4.8 4.5 4.5 3.1 Temperature of cold insulator 24 21 19 16 24 25 25 19 after one hour (° C.)

TABLE 2 Example Example Example Example Example Comp. 9 10 11 12 13 example 1 Melting point of latent heat — 16 16 7 25 — storage medium (° C.) Content of capsule containing 0 5 50 20 20 — latent heat storage medium (% by weight) Asker hardness F of gel material 29 31 52 34 35 23 Spring constant of cold insulator 0.29 0.31 0.85 0.38 0.39 0.16 (N/mm) Hysteresis loss of cold insulator 13 5 82 12 9 73 (%) Weight of cold insulator (g) 1300 1300 1300 1300 1300 1000 Thickness of cold insulator (mm) 35 35 35 35 35 36 Comfort during sleep 4.9 4.8 1.3 4.4 4.5 1.1 Temperature of cold insulator 36 36 16 36 36 20 after one hour (° C.)

As is clear from Table 1 and Table 2, any of the pillows of Examples 1 to 8, in particular, kept moderate coolness for a long period of time, and was predetermined to have a hardness and resilient property to fall within an appropriate range. Thus, these exhibited favorable comfort during sleep. To the contrary, according to Example 12 with a melting point of the latent heat storage medium being 7° C., an effect to store the latent heat is not exerted because the temperature attained by previous cooling is 7° C. Accordingly, there arises a problem of impossible retention of an appropriate temperature. Also, according to Example 13 in which melting point of the latent heat storage medium is too high, the temperature of the cold insulator is rapidly elevated to be higher than the temperature suited for accomplishing a quiet sleep. Therefore, there was a problem of insufficient effect to assist to fall asleep, which may result in wakefulness.

According to the pillow of Comparative Example 1, although moderate coolness could be kept, it involved a problem of absence of the restoring property (too great hysteresis loss), leading to deteriorated comfort during sleep. In Example 9, the latent heat storage medium was not include, while the content of the latent heat storage medium was too small in Example 10. Therefore, the temperature of the cold insulator became higher than the temperature to achieve a quiet sleep in an early stage, thereby causing problems of wakefulness due to insufficient effect to assist to fall asleep. Also, according to Example 11 in which the content of the latent heat storage medium is too great, compression stress and hysteresis loss became too great. Thus, the product became too hard as a pillow, leading to a problem of deteriorated effect to assist to fall asleep, and reduced comfort during sleep.

The description herein above is merely for an illustrative example, and various modifications can be made without departing from the principles of the present invention. 

1. A pillow which comprises: a cold insulator having a film for inclusion, and a gel material which is internally included in said film for inclusion and which comprises a crosslinked polymer that is not in a swelled state with a medium; and a main body having a concave portion which is open in the central part of the side wall thereof and which is constituted so that the said cold insulator is mounted in said concave portion.
 2. The pillow according to claim 1 wherein said gel material comprises 10% by weight or greater and 40% by weight or less of a latent heat storage medium having a melting point of 10° C. or greater and 20° C. or less, in a state being encased in a capsule of a resin film.
 3. The pillow according to claim 1 wherein said gel material comprises 10% by weight or greater and 40% by weight or less of a latent heat storage medium having a melting point of 10° C. or greater and 20° C. or less, being in a powder form having a particle size of 1 μm or greater and 50 μm or less, and comprising an organic compound, in a state being encased in a capsule of a synthetic resin film.
 4. The pillow according to claim 1 wherein surface temperature of said cold insulator at a position in contact with the neck region is kept at 5° C. or greater and 25° C. or less for at least 1 hour, when an adult man with a body temperature of approximately 36° C. lies thereon in an atmosphere of at 26° C. after setting the temperature of said cold insulator to be 5° C.
 5. The pillow according to claim 1 wherein said cold insulator has a spring constant of 0.1 N/mm or greater and 0.7 N/mm or less and a hysteresis loss of 5% or greater and 50% or less, as measured upon compression with a compressing element having a diameter of 10 mm at a testing rate of 30 mm/min, when the temperature of said cold insulator is set to be 20° C.
 6. The pillow according to claim 1 wherein said gel material comprises an unfoamed polyurethane resin, and has an Asker F hardness of 10 or greater and 50 or less.
 7. The pillow according to claim 1 wherein said cold insulator is in a sheet form.
 8. The pillow according to claim 1 wherein said cold insulator is in a sheet form having a thickness of equal to or less than 25 mm.
 9. The pillow according to claim 1 wherein the height of said concave portion is equal to or greater than one third of the height of said side wall.
 10. A combination which comprises: a cold insulator in a sheet form having a film for inclusion, and a gel material which is internally included in said film for inclusion and which comprises a crosslinked polymer that is not in a swelled state with a medium; and a container for encasing said cold insulator rolled or folded. 